The invention relates to a method of discharging sewage and to a control apparatus for carrying the method into effect.
A method for discharging sewage by vacuum is described, for example, in German Patent Specification No. 24 55 551. In the prior method, sewage is first collected at a connection point and then drawn off in a specific quantity by vacuum, air being sucked into the vacuum sewage pipe behind the sewage. Each suction operation is initiated by means of a suction valve unit on accumulation of about 10-15 liters of sewage. After the sewage has been sucked off out of the preliminary storage tank, the sewage suction valve is kept open a little longer through a time delay. In this manner, the air necessary for conveyance of the sewage is drawn into the sewage pipe through the sewage suction valve, which has been left open, after the sewage. That is to say, the necessary air is sucked in afterwards immediately between the comparatively small portions of sewage.
A control apparatus for carrying the described method into effect is known from German Patent Specification No. 24 62 295.
In clubhouses of sports grounds, camp sites, public facilities such as toilet installations, inns, etc., so much sewage is produced within a short time as a result of the simultaneous use of several toilets, showers and washbasins that the relatively small preliminary storage tank or basin is constantly full and, consequently, at each suction operation, only sewage is passed into the sewage pipe by way of the sewage suction valve. Consequently, the vacuum sewage pipe is constantly further filled, but the sewage in the pipe is not transported because no air for conveyance or only very little air can be drawn in as well. The entire run or line ceases to function and can only be made to work again if air is fed forcibly into the pipe at a plurality of points. This method, however, is very time-consuming and associated with a disturbance of operation.
The problem underlying the invention is to provide a method of discharging sewage by vacuum and the associated control apparatus which work reliably even where there is considerable production of sewage.